Here’s another home-made version of something you can buy in the shops – the vortex cannon is great fun to play with, and has lots of scope for inventing games which require you to knock things over with a gust of air. As I show in the video, if you’ve got some incense, it’s easy to use the same device to make smoke-rings! See if you can make a big ring and then send a small ring flying through it…

TOP TIP: If you don’t have a plastic bottle to hand, you could probably use a large yoghurt pot, or even the tube from a roll of toilet paper or kitchen towel to make your vortex cannon using the same basic idea. Feel free to experiment but please be safe and take extra care when cutting plastic containers.

EXTRAS: written instructions and the science of how smoke rings are formed can be found in this piece I wrote for BBC Focus Magazine. Below is a video of a vortex cannon being used to blow down a brick “house”, made by the legendary Jem Stansfield, a lovely man and brilliant engineer who I had the pleasure of working with many years ago.

MORE GOOD STUFF: Click here for more activities. I’ll be publishing more videos of activities from my book over the coming weeks. Check back here, follow me on Twitter or subscribe to my YouTube channel to make sure you don’t miss them.